U.S. patent number 5,420,093 [Application Number 08/201,942] was granted by the patent office on 1995-05-30 for catalyst based on silica and sulfuric acid and its use for the alkylation of paraffins.
This patent grant is currently assigned to Institut Francais du Petrole. Invention is credited to Eric Benazzi, Jean-Francois Joly, Christian Marcilly.
United States Patent |
5,420,093 |
Joly , et al. |
* May 30, 1995 |
Catalyst based on silica and sulfuric acid and its use for the
alkylation of paraffins
Abstract
Catalyst based on silica and sulfuric acid and its use in the
catalytic alkylation of isobutane and/or isopentane in the presence
of at least one olefin having 3 to 6 carbon atoms per molecule. The
catalyst may contain an additive, e.g., B(OH).sub.3, HBF.sub.4,
H.sub.3 PO.sub.4, FSO.sub.3 H, CF.sub.3 SO.sub.3 H, SbF.sub.5,
CF.sub.3 COOH and SO.sub.3.
Inventors: |
Joly; Jean-Francois (Paris,
FR), Marcilly; Christian (Houilles, FR),
Benazzi; Eric (La Celle Saint Cloud, FR) |
Assignee: |
Institut Francais du Petrole
(Rueil-Malmaison, FR)
|
[*] Notice: |
The portion of the term of this patent
subsequent to August 9, 2011 has been disclaimed. |
Family
ID: |
27252527 |
Appl.
No.: |
08/201,942 |
Filed: |
February 25, 1994 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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966648 |
Oct 26, 1992 |
5336833 |
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Foreign Application Priority Data
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Oct 25, 1991 [FR] |
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91 13303 |
Feb 28, 1992 [FR] |
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92 02482 |
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Current U.S.
Class: |
502/216; 585/723;
585/730; 585/731 |
Current CPC
Class: |
C07C
2/62 (20130101); C07C 9/14 (20130101); B01J
21/08 (20130101); B01J 27/02 (20130101); B01J
27/053 (20130101); B01J 27/06 (20130101); B01J
31/0215 (20130101); B01J 35/023 (20130101); B01J
35/08 (20130101); B01J 35/1009 (20130101); B01J
35/1014 (20130101); B01J 35/1028 (20130101); B01J
35/1038 (20130101); B01J 35/1042 (20130101); B01J
35/1047 (20130101); B01J 37/0201 (20130101); B01J
37/06 (20130101); C07C 2/62 (20130101); C07C
2521/08 (20130101); C07C 2527/02 (20130101); C07C
2527/054 (20130101); C07C 2527/12 (20130101); C07C
2527/133 (20130101); C07C 2527/173 (20130101); C07C
2531/025 (20130101); C07C 2531/04 (20130101); B01J
2231/323 (20130101); C07C 2521/02 (20130101) |
Current International
Class: |
B01J
27/06 (20060101); B01J 27/02 (20060101); B01J
31/02 (20060101); B01J 27/053 (20060101); C07C
2/62 (20060101); C07C 2/00 (20060101); B01J
027/053 () |
Field of
Search: |
;585/723,731,730
;502/216 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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47540 |
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Jul 1981 |
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EP |
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259105 |
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Aug 1987 |
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EP |
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303005 |
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May 1988 |
|
EP |
|
Other References
Fluka Catalog (1993-1994), p. 1162..
|
Primary Examiner: Pal; Asok
Attorney, Agent or Firm: Millen, White, Zelano &
Branigan
Parent Case Text
RELATED APPLICATION
This application is a continuation-in-part of U.S. Ser. No.
07/966,648, filed Oct. 26, 1992, now U.S. Pat. No. 5,336,833 which
is incorporated herein by reference.
Claims
What is claimed is:
1. A catalyst comprising silica and an acid wherein the acid
comprises 5% to 100% by weight of a sulfuric acid, and wherein the
acid is in a solid phase state in the silica, the silica having
been calcined and then impregnated by said acid and having a
specific surface of 0.01 to 1500 m.sup.2 /g, an average particle
diameter of 5 to 150 .mu.m and a total pore volume of 0.005 to 1.5
cm.sup.3 /g, the acid occupying 5% to 100% of the total pore
volume.
2. The catalyst of claim 1, wherein the silica, prior to
impregnation by the acid, contains at the most 5% impurities.
3. The catalyst of claim 1, wherein the acid also contains at least
one additive.
4. The catalyst of claim 3, wherein the additive is H.sub.3
PO.sub.4, B(OH).sub.3, BF.sub.4 H, FSO.sub.3 H, CF.sub.3 COOH,
SbF.sub.5, CF.sub.3 SO.sub.3 H or SO.sub.3.
5. The catalyst of claim 3, wherein the additive is sulfur
trioxide, SO.sub.3, the sulfur trioxide weight content in said acid
being from 0.01 to 60%.
6. The catalyst of claim 3, wherein the acid contains sulfuric
acid, sulfur trioxide and boric acid, the sulfuric trioxide weight
content in said acid being from 0.01 to 60% and the boric acid
weight content in the mixture comprising sulfuric acid and sulfur
trioxide being from 0.01 to 50%.
7. The catalyst of claim 1, wherein the silica has a specific
surface of 0.01 to 150 m.sup.2 /g.
8. The catalyst of claim 1, wherein the silica has a specific
surface of 0.01 to 50 m.sup.2 /g, and the total pore volume is
0.005 to 1 cm.sup.3 /g.
9. The catalyst of claim 1, wherein the sulfuric acid concentration
in the acid is 88-100% by weight.
10. The catalyst of claim 1, wherein the average particle diameter
of the silica is 5 to 110 .mu.m.
11. The catalyst of claim 1, wherein the average particle diameter
of the silica is 5 to 80 .mu.m.
12. The catalyst of claim 2, wherein the sulfuric acid and the
additive comprise 60% to 90% of the total pore volume.
13. The catalyst of claim 12, wherein the sulfuric acid
concentration in the acid is 88-100% by weight.
14. In a process for the catalytic alkylation of at least one of
isobutane and isopentane with at least one olefin having 3-6 carbon
atoms per molecule, the improvement which comprises employing a
catalyst comprising silica and an acid, wherein the acid comprises
5% to 100% by weight of sulfuric acid and wherein the acid is in a
solid phase state in the silica, the silica having been calcined
and then impregnated by said acid and having a specific surface of
0.01 to 1500 m.sup.2 /g, an average particle diameter of 5 to 150
.mu.m and a total pore volume of 0.005 to 1.5 cm.sup.3 /g, the acid
occupying 5% to 100% of the total pore volume.
15. The process of claim 14, wherein the silica, prior to
impregnation by the acid, contains at the most 5% impurities.
16. The process of claim 14, wherein the acid also contains at
least one of B(OH).sub.3, HBF.sub.4, H.sub.3 PO.sub.4, FSO.sub.3 H,
CF.sub.3 SO.sub.3 H, SbF.sub.5, CF.sub.3 COOH and SO.sub.3.
17. The process of claim 14, wherein the average particle diameter
of the silica is 5 to 110 .mu.m.
18. The process of claim 14, wherein the average particle diameter
of the silica is 5 to 80 .mu.m.
19. The process of claim 14, wherein the sulfuric acid
concentration in the acid is 88-100%.
20. The process of claim 14, wherein the reaction temperature is
below 0.degree. C.
21. The process of claim 14, wherein the catalyst is used in a
moving bed.
22. The process of claim 14, wherein the catalyst is used in a
fluid bed.
23. The process of claim 14, wherein the catalyst is used suspended
in a liquid phase of the reagents.
Description
BACKGROUND OF THE INVENTION
The present invention relates to a catalyst based on silica and
sulfuric acid and its use in the catalytic alkylation of isobutane
and/or isopentane by means of at least one olefin, which makes it
possible to obtain at least one product, e.g., in the group
constituted by dimethyl butanes, trimethyl pentanes, trimethyl
hexanes and trimethyl heptanes.
It is known that for the supply of internal combustion and
controlled ignition engines and in particular those having a high
compression ratio, it is particularly interesting to have high
octane fuels, i.e., essentially constituted by highly branched
paraffin hydrocarbons. The alkylation of isoparaffins (isobutane
and isopentane) by olefins containing 3 to 6 carbon atoms per
molecule makes it possible to obtain such products. This reaction
requires the use of very acid catalysts, with the aim of reducing
unwanted reactions, such as olefin hydride extraction and
polymerization reactions, which supply only slightly branched
hydrocarbons with a low octane number and unsaturated hydrocarbons,
cracking reactions and disproportionation reactions.
Existing processes for the production of hydrocarbons by the
alkylation of isobutane by olefins use either sulfuric acid or
hydrofluoric acid as the catalyst. In these processes, the acid
catalyst constitutes a liquid phase, which is contacted with the
liquid olefin-isobutane mixture to form an emulsion. These
processes are expensive and cause serious problems with regards to
the safety of personnel and the environment. In order to obviate
these problems, different catalytic systems of sulfuric and
hydrofluoric acids in the liquid phase have been investigated.
In order to catalyze alkylation reactions of isoparaffins by
olefins, a proposal has already been made to develop acid catalysts
from numerous acid solids of various types. Among the families of
acid catalysts, reference can be made to molecular sieves (e.g.,
U.S. Pat. No. 3,236,762, U.S. Pat. No. 3,251,902, U.S. Pat. No.
3,644,565, U.S. Pat. No. 4,377,721, U.S. Pat. No. 4,384,161 and
U.S. Pat. No. 4,300,015), macromolecular resins, optionally
associated with BF.sub.3 (e.g., U.S. Pat. No. 3,855,342, U.S. Pat.
No. 3,855,343, U.S. Pat. No. 3,862,258 and U.S. Pat. No.
3,879,489), perfluor ine resins of the Nation type (e.g., U.S. Pat.
No. 4,056,578 and U.S. Pat. No. 4,038,213) Lewis and/or Bronsted
acids deposited on various inorganic supports (e.g., U.S. Pat. No.
3,975,299, U.S. Pat. No. 3,852,371 and U.S. Pat. No. 3,979,476),
chlorinated alumina (e.g., U.S. Pat. No. 3,240,840, U.S. Pat. No.
3,523,142, U.S. Pat. No. 3,607,859, U.S. Pat. No. 3,523,142, U.S.
Pat. No. 4,066,716, U.S. Pat. No. 4,083,800 and U.S. Pat. No.
4,066,716) graphites intercalated by Lewis and/or Bronsted acids
(e.g., U.S. Pat. No. 4,083,885, U.S. Pat. No. 4,116,880, U.S. Pat.
No. 4,128,596 and U.S. Pat. No. 3,976,714) and anions deposited on
oxide supports such as ZrO.sub.2 /SO.sub.4 (e.g., JP-01288329,
JP-01245953 and JP-61242641). These solids lead to the production
of branched isoparaffins, but suffer from several major defects,
including the use of often very high isobutane/olefin molar ratios
in order to limit the extent of secondary reactions and low
stability in time of the catalytic activity (inhibition of the
catalyst by the deposition of unsaturated oligomers), so that said
catalysts frequently have to be regenerated. Moreover, the limited
acidity of certain acid solids, such as, e.g., molecular sieves,
makes it necessary to use high reaction temperatures, which is
prejudicial to the obtaining of high octane hydrocarbons.
SUMMARY OF THE INVENTION
In the present invention, a novel catalyst has been discovered
making it possible to obtain paraffin compounds with high levels of
branching and high octane numbers by the alkylation of isoparaffin
(isobutane and/or isopentane) by at least one olefin having 3 to 6
carbon atoms per molecule. This novel catalyst is advantageously
used in a process wherein the olefin and/or a mixture of olefins is
introduced into the reactor in the liquid phase and mixed with the
isoparaffin and/or the isoparaffin mixture. The catalyst is used a
solid, moving or fluid bed, or suspended in the liquid phase of the
reagents subject to an effective stirring.
The catalyst according to the present invention contains silica and
an acid phase comprising sulfuric acid, the silica being partly or
totally impregnated by said acid phase. The sulfuric acid
concentration is advantageously from 5 to 100% by weight,
preferably 50 to 100% by weight and, in an even more preferred
manner, from 88 to 100% by weight.
Numerous silica sources can be used. The specific surface of said
silica is from 0.01 to 1500 m.sup.2 /g, preferably from 0.01 to 150
m.sup.2 /g and, in an even more preferred manner, from 0.01 to 50
m.sup.2 /g. The total pore volume of said silica is from 0.005 to
1.5 cm.sup.3 /g and preferably from 0.005 to 1 cm.sup.3 /g. The
silica support is preferably substantially spherical and preferably
has an average diameter of 5 to 150 .mu.m, more preferably 5 to 110
.mu.m and, particularly, 5 to 80 .mu.m. The silica can contain
impurities such as, e.g., oxides, alkali, alkaline earths, aluminum
compounds or any other known impurity, the total quantity of said
impurities not exceeding 5 and preferably 2% by weight, based on
the silica. Such silica materials may be obtained, for example,
from PQ, Akzo, Rhone Poulenc or Solvay.
During the impregnation of said silica, the acid phase comprising
the H.sub.2 SO.sub.4 acid solution occupies a fraction of the total
pore volume of 5 to 100%. The thus-obtained catalyst is
characterized by a specific surface from 0.01 to 500 m.sup.2 /g,
preferably from 0.01 to 150 cm.sup.2 /g and, in an even more
preferred manner, from 0.01 to 40 m.sup.2 /g.
It is possible to add to the acid phase at last one additive with a
view to improving the catalytic performance characteristics. The
additive is chosen from within the group formed by: H.sub.3
PO.sub.4, B(OH).sub.3, BF.sub.4 H, FSO.sub.3 H, CF.sub.3 COOH,
SbF.sub.5, CF.sub.3 SO.sub.3 H and SO.sub.3.
In this case, during the impregnation of the silica, the acid phase
comprising sulfuric acid and at last one additive occupies a
fraction of the total pore volume of the silica of 5 to 100% and
preferably 60 to 90%. The thus-obtained catalyst is characterized
by a specific surface of 0.01 to 500 m.sup.2 /g, preferably 0.01 to
150 m.sup.2 /g and in an even more preferred manner, 0.01 to 40
m.sup.2 /g.
An even more preferred additive, according to the present
invention, is sulfur trioxide SO.sub.3. When the latter is used,
the acid phase incorporating at least the sulfuric acid and the
sulfur trioxide is often referred to as "oleum". The sulfur
trioxide weight content in the oleum used is from 0.01 to 60% and
preferably 1 to 30%. When said oleum is used for impregnation, it
is preferable to add to said oleum a supplementary additive with a
view to increasing the acidity of the catalyst and therefore
improve the catalytic performance characteristics thereof. The
preferred supplementary additive is boric acid (H.sub.3 BO.sub.3),
the boric acid weight content within the mixture comprising the
sulfuric acid and the sulfur trioxide advantageously being 0.01 to
50% and, in an even more preferred manner, 0.01 to 10%.
The preparation process of the catalyst according to the invention
comprises two stages. In a first stage, the silica is calcined at a
temperature exceeding 50.degree. C., preferably exceeding
80.degree. C. and, in an even more preferred manner, at 200.degree.
to 600.degree. C., e.g., at approximately 500.degree. C. The
duration of said calcination stage is normally between 10 minutes
and 50 hours. Calcination can be carried out in the presence of air
or an air/nitrogen mixture with a flow rate of 0.001 to 10 l/h/g.
The second stage consists of the impregnation of said calcined
silica by the acid phase. In order to carry out this stage, it is
possible to use all known procedures. When kept at a temperature
below the melting point of said acid phase and protected from
moisture, the catalyst according to the invention thus contains
solid acid phase-impregnated silica, i.e., the acid is present in a
solid state phase impregnated in the silica support.
The catalyst according to the present invention is used in the pure
state or diluted with various materials having little catalytic
activity in the considered reaction such as, e.g., silica, alumina,
magnesia or various clays such as, e.g., bentonite, montmorillonite
or kaolin.
The isoparaffin-olefin mixture is introduced into the reactor at a
space velocity, expressed as olefin weight introduced per weight
unit of catalyst and per hour is from 0.001 to 10 h.sup.-1 and
preferably 0.002 to 2 h.sup.-1. The mixture can also be formed
within the reactor. In all cases, the thus-formed mixture is in the
reactor under pressure and temperature conditions such that the
hydrocarbon mixture remains liquid on the catalyst and the
constituents of the catalyst remain in the solid state.
The reaction temperature can be from -50.degree. to 150.degree. C.,
but we have surprisingly discovered that the catalytic performance
characteristics are greatly improved when the reaction temperature
is below the crystallization temperature of the acid phase used for
impregnating the silica. The reaction temperature must then be
below +6.degree. C., preferably at 0.degree. C., more preferably
below -5.degree. C. and even more preferably below -10.degree. C.
The reactor pressure is adequate to maintain the hydrocarbons in
the liquid state in the reactor.
One of the advantages of the catalyst according to the invention
when the acid phase is mainly constituted by sulfuric acid is the
possibility of alkylating isobutane and/or isopentane at
temperatures below -10.degree. C. and which can reach -30.degree.
C. Thus, L. F. Albright et al., in Ind. Eng Chem. Res. 1988, 27,
pp. 381-397, very clearly indicate the interest in carrying out
isobutane alkylation in the presence of sulfuric acid at
temperatures below 0.degree. C. Namely a very significant reduction
in secondary reactions and, therefore, in the consumption of the
catalyst is obtained, while improving the quality of the
hydrocarbons obtained. The published results only refer to tests
carried out on a laboratory scale. The disadvantage associated with
the use of such temperatures is the necessity of extremely powerful
stirring, in view of the very high viscosity of the sulfuric acid
in solution at such temperatures, with even an impossibility of
stirring if the temperature is below the melting point of sulfuric
acid. The catalyst according to the invention makes it possible to
carry out the alkylation of isobutane and/or isopentane at these
very low temperatures without any need for increasing the power of
the stirring, the sulfuric acid phase being contained within the
porosity of the silica.
In order to limit the secondary reactions, it is possible to use an
isoparaffin excess compared with the olefin. For example, in the
case of the alkylation of isobutane by a butene, the isobutane can
be introduced in the pure state into the charge or in the form of a
mixture of butanes, e.g., containing at least 40% of isobutane.
Moreover, it is possible to introduce a pure butene or a mixture of
isomeric butenes. In all cases, the molar isobutane/butene ratio in
the charge is from 1 to 100, preferably 3 to 50 and, in an even
more preferred manner, 5 to 10. The reaction products can be
regularly controlled by measuring the bromine number, e.g., in
accordance with draft French standard Pr. M. 07.071 of March
1969.
When the nature of the catalyst and the catalyst operating
conditions are carefully chosen (particularly the temperature), the
catalyst according to the invention makes it possible to produce
products for the alkylation of paraffins by olefins, which are of
interest as fuels for engines and petrol constituents and which,
e.g., comprise at least 60 molar % paraffins having 8 carbon atoms
per molecular and less than 1 molar % of unsaturated compounds, the
paraffins having 8 carbon atoms per molecule with 70 to 98 molar %
of trimethyl pentanes.
Another advantage of the catalyst according to the invention is the
possibility of low temperature alkylation of isobutane with
mixtures of olefins having 3 to 6 carbon atoms per molecule, where
the proportion of olefins having at least 5 carbon atoms per
molecular is very high (at least 10 and preferably at least 40% by
weight).
Without further elaboration, it is believed that one skilled in the
art can, using the preceding description, utilize the present
invention to its fullest extent. The following preferred specific
embodiments are, therefore, to be construed as merely illustrative,
and not limitative of the remainder of the disclosure in any way
whatsoever.
In the foregoing and in the following examples, all temperatures
are set forth uncorrected in degrees Celsius and unless otherwise
indicated, all parts and percentages are by weight.
The entire disclosures of all applications, patents and
publications, cited above and below, and of corresponding
applications French 91/13.303, filed Oct. 25, 1991 and French
92/02.482, filed Feb. 28, 1992, are hereby incorporated by
reference.
EXAMPLES
Example 1 (according to the invention)
Sulfuric acid catalyst on silica
Preparation of catalyst A
16 g of macroporous silica with a specific surface of 27 m.sup.2 /g
and a total pore volume of 0.78 cm.sup.3 /g are activated by
calcination in air for 4 hours at 500.degree. C. The substantially
spherical particles had an average diameter of about 110 .mu.m. The
thus-activated silica is kept under argon. This is followed by the
dry impregnation of 14 g of said silica by 20 g of a 96% by weight
sulfuric acid solution. The thus-obtained solid, called catalyst A,
contains 20 g of sulfuric acid and 14 g of silica and is kept under
argon at -18.degree. C.
Alkylation of isobutane by 1-pentene
34 g of catalyst A prepared according to the aforementioned method
is introduced into a Fischer & Porter-type glass reactor with a
volume of 360 ml and previously purged under an argon flow. The
reactor containing the catalyst A is then sealed, placed under an
initial vacuum and then cooled to -20.degree. C. 80 cm.sup.3 of
isobutane are then added to the reactor containing the catalyst
accompanied by stirring with a magnetic bar, said reactor being
immersed in a cold bath at -20.degree. C. The catalyst A+isobutane
system is kept stirred for 30 minutes in order to render the
temperature uniform. There is a regular addition of 1.73 cm.sup.3
of 1-pentene per hour for a total time of 12 hours, the reactor
temperature being maintained at -12.degree. C. for the entire
injection period.
Following the reaction, the hydrocarbon phase is removed from the
reactor and then the isobutane is slowly evaporated, followed by
the collection of the alkylate, which is analyzed by gas
chromatography. Its weight composition is given in the following
Table 1. The olefin conversion is 100%.
TABLE 1 ______________________________________ iC.sub.5 3.20
C.sub.6 2.65 C.sub.7 0.88 C.sub.8 11.70 C.sub.9 75.40 C.sub.9.sup.+
6.17 ______________________________________
The C.sub.8 fraction contains 90.3% by weight of trimethyl pentanes
and the C.sub.9 fraction 90.8% of trimethyl hexanes.
Alkylation of isobutane by an olefin C.sub.4 -C.sub.9 fraction
Use is made of a catalyst prepared in the same way as catalyst A
described hereinbefore for the alkylation of isobutane by an olefin
C.sub.4 -C.sub.6 fraction. The fraction used has the following
composition:
10% 2-butene
35% 1 -butene
55% hexenes.
The hexene fraction contains 60% of 2-methyl-2-pentene and 40% of
2-hexene.
The previously described procedure is used for the alkylation
reaction and 90 ml of isobutane are alkylated by 7.4 ml of the
olefin charge described hereinbefore for 41/2 hours at a
temperature of -15.degree. C. The alkylate is collected and
analyzed by gas chromatography. There is a total conversion of the
olefins. The weight composition of the alkylate obtained is given
in the following Table 2.
TABLE 2 ______________________________________ iC.sub.5 3 C.sub.6
18 C.sub.7 3 C.sub.8 25 C.sub.9 25 C.sub.9.sup.+ 26
______________________________________
The C.sub.6 fraction contains 73% of methyl pentanes, the C.sub.8
fraction contains 92% by weight of trimethyl pentanes and the
C.sub.9 fraction contains 89% of trimethyl hexanes.
Example 2 (according to the invention)
Sulfuric acid catalyst on silica
Preparation of catalyst B
15 g of macroporous silica with a specific surface of 27 m.sup.2 /g
and a total pore volume of 0.78 cm.sup.3 /g are activated by
calcination in air for 2 hours at 500.degree. C. The substantially
spherical particles had an average diameter of about 110 .mu.m. The
thus-activated silica is kept under argon. This is followed by the
dry impregnation of 13.7 g of said silica by 18.96 g of a 96% by
weight sulfuric acid solution. The thus-obtained solid, called
catalyst B, contains 18.96 g of sulfuric acid and 13.7 g of silica
and is kept under argon at -20.degree. C.
Alkylation of isobutane by 1-butene
32 g of catalyst B prepared according to the method described
hereinbefore are introduced into a Fischer & Porter-type glass
reactor with a volume of 360 ml and previously purged under an
argon flow. The reactor containing catalyst B is then sealed,
placed under an initial vacuum and cooled to -20.degree. C. 57
cm.sup.3 of isobutane are then added to the reactor containing the
catalyst and accompanied by stirring by a magnetic bar, said
reactor being immersed in a cold bath at -20.degree. C. The
catalyst B+isobutane system is kept under stirring for 30 minutes,
in order to render the temperature uniform. There is a regular
addition of 1.70 cm.sup.3 of 1-butene/hour for a total period of 6
hours, the reactor temperature being maintained at -7.degree. C.
for the duration of the injection.
Following the reaction, the hydrocarbon phase is removed from the
reactor and then the isobutane is slowly evaporated and the
alkylate collected, which is analyzed by gas chromatography. Its
weight composition is given in the following Table 3. The olefin
conversion is 100%.
TABLE 3 ______________________________________ iC.sub.5 1.26
C.sub.6 3.16 C.sub.7 2.62 C.sub.8 83 C.sub.9 1.70 C.sub.9.sup.+
8.26 ______________________________________
The C.sub.8 fraction contains 89.7% by weight trimethyl pentanes
and the C.sub.9 fraction 92.2% of trimethyl hexanes.
Example 3 (according to the invention)
Sulfuric acid catalyst+sulfur trioxide on silica
Preparation of catalyst C 14 g of macroporous silica with a
specific surface of 27 m.sup.2 /g and a pore volume of 1 cm.sup.3
/g are activated by calcining in air for 4 hours and at 500.degree.
C. The substantially spherical particles had an average diameter of
about 110/.mu.m. The thus-activated solid is kept under argon. This
is followed by the dry impregnation of 10 g of the calcined solid
by 7 cm.sup.3 of the mixture constituted by 80% by weight sulfuric
acid (99.99%) and 20% by weight sulfur trioxide. The thus-obtained
catalyst C contains 13.5 g of oleum and 10 g of silica and is kept
under an argon atmosphere at -18.degree. C.
Alkylation of isobutane by 1-butene using catalyst C
20 g of catalyst C prepared according to the method described in
Example 3 are introduced into a Fischer & Porter-type glass
reactor with a volume of 360 cm.sup.3 and previously purged under
an argon flow. The reactor containing the catalyst is then sealed
and placed under an initial vacuum, followed by cooling at
-20.degree. C. 72 cm.sup.3 of isobutane are then added to the
reactor containing the catalyst, accompanied by stirring with
magnetic bar, said reactor being immersed in a cold bath at
-20.degree. C. Stirring is maintained of the catalyst+isobutane
system for 30 minutes in order to render the temperature uniform.
There is a regular addition of 50 cm.sup.3 of a mixture constituted
by 24 volume % of 1-butene and 76 volume % of isobutane for a total
period of 10 hours, the reactor temperature being maintained at
-15.degree. C. throughout the injection period.
After reaction, the hydrocarbon phase is removed from the reactor
and the isobutane slowly evaporated. The alkylate is collected and
analyzed by gas chromatography, its weight composition being given
in Table 4.
TABLE 4 ______________________________________ iC.sub.5 1.5 C.sub.6
1.1 C.sub.7 1.9 C.sub.8 90 C.sub.9 1.2 C.sub.9.sup.+ 4.3
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The olefin conversion is 98%. The alkylation yield is 200%, based
on the transformed olefin. The C.sub.8 fraction contains 89% by
weight of trimethyl pentanes.
Example 4 (according to the invention)
Preparation of a sulfuric acid catalyst+sulfur trioxide+boric acid
on silica
Preparation of catalyst D
For the preparation of catalyst D, use is made of 13 g of the same
macroporous silica as that used for the preparation of catalyst C,
the calcination conditions being identical. Preparation takes place
of a mixture constituted by oleum and boric acid and,for this
purpose, use is made of 7 cm.sup.3 of the same mixture as that used
for obtaining catalyst C and to which is added 0.81 g of anhydrous
boric acid. This gives 14.31 g of a mixture of sulfuric acid
(75.47% by weight), sulfur trioxide (18.86% by weight) and boric
acid (5.67% by weight).
This is followed by the dry impregnation of 11 g of calcined silica
by all the mixture described hereinbefore. The thus-obtained
catalyst D contains 14.31 g of acid phase and 11 g of silica and is
kept under an argon atmosphere at -18.degree. C.
Alkylation of isobutane by 1-butene using catalyst D
The catalytic test of alkylating isobutane by 1-butene is repeated
under the same experimental conditions as those described in
Example 3 and the results are given in the following Table 5.
TABLE 5 ______________________________________ iC.sub.5 0.8 C.sub.6
0.5 C.sub.7 1.1 C.sub.8 94.6 C.sub.9 0.9 C.sub.9.sup.+ 2.1
______________________________________
The alkylation yield is 201%, based on the transformed olefin. The
C.sub.8 fraction contains 92% by weight trimethyl pentanes. This
table shows the interest of adding boric acid to the mixture of
sulfuric acid and sulfur trioxide and this represents one of the
preferred embodiments of the invention.
The preceding examples can be repeated with similar success by
substituting the generically or specifically described reactants
and/or operating conditions of this invention for those used in the
preceding examples.
From the foregoing description, one skilled in the art can easily
ascertain the essential characteristics of this invention, and
without departing from the spirit and scope thereof, can make
various changes and modifications of the invention to adapt it to
various usages and conditions.
* * * * *